Sun-Powered Refrigerated Truck Trailer Slashes Diesel Emissions

April 30, 2018 by Carly Schaffner, @carlyschaffner

Keeping fresh goods refrigerated during transport is important for food safety, but it requires a lot of energy and creates pollution.

A solar-powered cooling system developed by eNow, a Warwick, R.I., builder of solar panels could address that problem. In one test, it cut harmful diesel emissions on a refrigerated truck trailer by almost 100 percent.

eNow put its system, dubbed “Rayfrigeration,” through real-world paces in the most severe conditions to ensure it works as effectively as its pollutant emitting counterpart.

Refrigerated, or reefer trucks, have two engines. One is part of the drivetrain, and the other keeps the trailer cold.

“The trailers have their own separate diesel engines on them, so they have their own fuel supply,” said Jeff Flath, eNow’s president and chief executive.

The company has focused on the transportation industry since its 2011 founding. It builds power systems for big rig air conditioning, lift gates for straight and semi-truck trailers, safety lighting for emergency vehicles and telematics systems that require an energy source to ensure batteries are always charged.

But reefer trucks are a different animal. By replacing the diesel engine with a battery, there is huge opportunity to cut fuel and maintenance costs, Flath said.

eNow All-Electric Reefer Trailer

eNow all-electric reefer trailer. (Photo: eNow)

eNow’s system integrates its panels into a battery pack that has enough energy to operate the complete trailer system, he said. A typical reefer truck is in service between eight and 12 hours per day.

The company also eliminated most greenhouse gases from a trailer’s on-board diesel-powered compressor.

Diesel and other fossil-fuel burning systems typically used to cool reefer trailers emit pollutants into the air such as hydrocarbons, carbon monoxide, nitrogen oxide, or NOx, and particulate matter.

The emissions from the trailer unit often go unmonitored.

“Many of the small engines used to power the conventional refrigeration units are essentially unregulated and so are highly polluting,” said Bill Van Amburg, executive vice president of Pasadena-based clean emissions technologies booster CalStart.

In many cases they are more polluting than the big engines powering the trucks, Van Amburg said.

This technology could help slash diesel emissions in a growing market.

“The reefer transportation industry is going to grow 12 to 17 percent per year because more and more goods are being transported,” Flath said.

Increased e-commerce is expanding last-mile delivery of all product types, including food delivery, and electrification of these trucks is part of a larger trend, Van Amburg said.

David Cooke, senior analyst at the Union of Concerned Scientists, said the California Air Resources Board identified lowering greenhouses gases emitted from reefer trailers as part of its overall clean air strategy.

“The board highlighted real concerns for refrigerated warehouse distribution centers where trailers sit idle when they’re being loaded,” Cooke said. “In a lot of cases they are just sitting there for long stretches of time.”

eNow’s green technology could allow motor carriers to “comply with idle reduction zones that limit engine run time while still keeping goods cold, Van Amburg said. “They also will reduce diesel emissions at delivery and loading points when people are in close proximity.”

To construct the power source, eNow used a lightweight solar system with advanced photovoltaic, or PV, panels and married it to a hybrid cooling system and an insulated truck box. The result is a nearly zero-emissions transport refrigeration unit.

In a nearly $1-million demonstration in the San Joaquin Valley, eNow installed its unit on a Class 7 Challenge Dairy delivery truck that distributes products to customers in Fresno, Calif., a city notorious for extreme heat in summer months.

The air pollution control district in the region footed half the bill.

“Some days temperatures reached around 112 degrees,” Flath said. “This was the rugged environment we wanted to make sure it could perform equal to a diesel system.”

The vehicle was used on average about eight hours per day. At night it returned to the distribution hub where the unit’s battery pack was recharged via “shore” power, which means electricity from the grid.

eNow all-electric Reefer trailer solar-battery charging monitor.

eNow all-electric reefer trailer solar-battery charging monitor. (Photo: eNow)

Between April and August — the five hottest months of the year — the team found that the Rayfrigeration system reduced NOx emissions by 98 percent compared with the original truck. Carbon monoxide was reduced by 86 percent, and particulate matter pollutants fell by 97 percent.

“We were more surprised at how much pollutants are produced by a diesel engine,” Flath said.

Average emissions of carbon monoxide over a four-day work week with an average delivery day of 7.7 hours plunged to 159 pounds from 2,252 pounds, according to eNow. NOx emissions dropped from 7,162 grams to just 1.

And by eliminating operations and maintenance costs associated with running a diesel engine, eNow was able to attain the initially projected savings of 90 percent.

“Electrifying refrigerated freight trucks is an environmental and economic win-win,” said Luke Tonachel, director of the clean vehicles and fuel project for the Natural Resources Defense Council.

Powering reefer systems with sun and electricity lessens “health-threatening” pollution and is cheaper than burning diesel, Tonachel said.

Now the company is adding to its repertoire. While the Challenge Dairy truck will continue to run its route in Fresno and collect data for the team, eNow will begin testing its solar unit on 53-foot Great Dane Class 8 trailer in May. The truck will be operated by C&S Wholesale Grocers.

Clean transport refrigeration units are a great example of how businesses can help preserve clean air while chilling our food, Tonachel said.

Read Next: Toyota’s Heavy-Duty Fuel Cell Truck Finally Hits the Road

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